The scavenging behaviour of ferrets (Mustela furo), feral cats (Felis domesticus), possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus) and harrier hawks (Circus approximans) on pastoral farmland in New Zealand: Implications for bovine tuberculosis transmission

Aims: To identify species that scavenge carcasses in pastoral habitats in N ew Zealand; to determine whether there were interspecific or intraspecific differences in scavenging behaviour and; to document any interspecific or i ntraspecific interactions occurring at carcasses. Methods: Scavenging by ferrets (Mustela furo), feral cats (Felis domesticus ), possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus) and har rier hawks (Circus approximans) was studied from autumn to midwinter on pas toral farmland near Palmerston (45S, 170E), Otago, New Zealand. Time-lapse video recorders and camera lens mounted with infra-red light illumination w ere used to monitor carcasses of 10 ferrets, 12 possums, 2 hedgehogs and 7 rabbits (Oryctolagus cuniculus) until they were totally scavenged. Results: Ferrets scavenged 5/8 ferret carcasses, 8/9 possum carcasses and 6 /7 rabbit carcasses encountered. Feral cats scavenged 3/8 ferret carcasses, 5/7 rabbit carcasses, and 3/8 possum carcasses encountered. Possums scaven ged 1/2 ferret carcasses and 3/4 rabbit carcasses encountered. The proporti on of encounters resulting in feeding on ferret carcasses differed between ferrets (45.7%) and possums (6.3%), and between possums and cats (29.7%). S imilarly, for possum carcasses, differences were found between ferrets (76. 6%) and possums (0%), ferrets and cats (60.6%) and possums and cats. No int erspecific differences were found in the proportion of encounters that resu lted in feeding on rabbit carcasses between ferrets (85.2%), possums (75%) and cats (73.1%). In 8/12 instances of ferrets coming into contact with oth er ferrets whilst feeding, ferrets fed together at the carcass. On I occasi on, 4 ferrets were recorded feeding together. In 7/8 instances where cats a nd ferrets came into contact over carrion, ferrets maintained possession or displaced the cat from the carcass. Conclusions: Communal carrion feeding by ferrets may facilitate intraspecif ic and interspecific transmission of bovine tuberculosis (caused by Mycobac terium bovis) by the consumption of contaminated carrion, fighting, or clos e-contact activities. Cannibalism may be one mechanism by which tuberculosi s is transmitted within ferret populations. Our results also suggest that p ossums may acquire infection from carrion, despite being mainly herbivorous .